Political ad spending in the U.S. is expected to rise a whopping 59 percent to about $10 billion in 2020 compared to the 2016 presidential election year, according to estimates by media agency GroupM. That sounds like a lot, and it is.

About $6.3 billion was spent on political ads in the 2016 U.S. election. That’s more than double what was spent in the 2004 campaign.

The demise of public financing has played a role in the spike. In 2008, Barack Obama became the first presidential candidate to reject federal campaign funds and no other presidential candidate has accepted federal money for the general election since.

The 2010 Citizens United case, which legalized unlimited spending by corporations and individuals, only fueled the trend, with super PACs now funneling money into advertising.

The report from GroupM predicts a future in which digital ads become a bigger part of total spending, though television remains a major player for now as well. Early numbers from Facebook show it reaping rewards from the 2020 campaign already. President Donald Trump has already spent around $5 million on Facebook ads this year, while former Vice President Joe Biden has spent about $1 million.